Transcript Occupational vibration syndrome

Occupational vibration syndrome
Department of Occupational Medicine
Finnish Institute of Occupational Health
Markku Sainio
Markku Vanhanen
Definitions
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Vibration
Hand-arm vibration (HAV)
Whole-body vibration (WBV)
Vibration white finger (VWF)
Hand-arm vibration syndrome (HAVS)
Raynaud's phenomenon
Electroneuromyograpy (ENMG)
Vibration
• Periodic motion of a body in alternate
opposite directions from a position of rest
• Mathematical "vector quantity"= described
by both a direction and a magnitude
– directions of vibration
– acceleration
• Present in most work settings where
mechanical equipment is used
Measurements and standards
• ACGIH TLVs 1984
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4 m/s2 < 8 hours a day
6 m/s2 < 6 hours a day
8 m/s2 < 2 hours a day
12 m/s2 < 1 hour a day
• ISO 5349 (1986)
– Standard for measurements over frequencies from 5 to
1500 Hz
• Mitä laatua käytetään, millaiset tasot aih tautia,
Dose-response curves and
threshold limits
– are not applicable to all tools
– are derived from chain-saw data
– do not take into account impulsiveness and high
frequency of many tools
Directive 2002/44/EC…
.. on the minimum health and safety
requirements regarding the exposure of
workers to the risks arising from physical
agents (vibration)...
– daily (8 h) exp. limit value
5 m/s2
– daily exp. action limit value 2,5 m/s2
HAV as occupational disease in Finland
1990-2001
ROD
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2001-4/2002
1999-2000
1997-98
1995-96
1993-94
1990-92 (3 yrs)
32
38
37
44
92
FIOH
10
16
17
7
18
37
Occupations (FIOH 1990-2001)
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Chain saw work
22
Construction worker 15
Miners+ drillers
15
Machine work,-repair,
tool makers
9
• Welders
5
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Pipework
4
Railroad or road work 3
Stonework
3
1-2 : dental technician,
teacher, painter, manufacture
of diff. devices, plastics
worker etc.
Exposure
• Vibration level, acceleration, frequency,
angles, impulses
• Duration, continuity, radiation of the
vibration (tool weight, grip strength, hand
position, exposure area)
• Smoking increases VWF prevalence, if > 20
cigarettes/d > 20 years
• Temperature
Hand-arm vibration syndrome (HAVS)
• Disease entity with separate components, all of
which may not be recognized at the same time:
• Circulatory disturbances
• secondary Raynaud: vasospasm with local finger
blanching
• Sensory and secondary motor disturbances
• local polyneuropathy: numbness, clumsiness
• Musculoskeletal disturbances (?)
• HAVS may lead to severe disease causing
permanent working disability
Hand-arm vibration syndrome
(HAVS)
• White finger symptoms are essential
– however, not always present
• Dose-related (quantity and quality of exposure)
• May be reversible, but usually irreversible and
progressive if exposure continues
• Smoking and cold exposure predisposing risk
factors
• Individual differences in susceptibility (other
causes of Raynaud???)
Symptoms
• Cold/damp (sometimes vibration) induced white
fingers
• However, also peripheral sensory reduction and
slight clumsiness without white fingers
• More proximal bone and joint symptoms occur
occasionally (may be due to ergonomic factors)
• Carpal tunnel syndrome and epicondylitis
coexist often
PATOPHYSIOLOGY
• Local oedema in nerve and perineural tissue
• Local damage in non-myelinated nerve
fibers  changes in blood vessels
vasoconstriction in cold
– mechanism: adrenergic reseptor damage in
vessel wallsalfa-2-reseptor predominance
Objective findings
• Vibration detection levels increase (damaged
thick myelin fibers)
• Temperature detection levels increase (damaged
thin myelin fibers)
• Two-point differentiation ability reduced
• Grip strength reduced
• Finger pletysmography: blood pressure of the
affected finger drops in cold exposure
• ENMG: sensory conduction velocities reduced
before motor velocities
Diagnosis I
• Exposure sufficient
• Exp. in Occupational med+neurology+fysiatry
• Clinical status: Sensory testing, grip strength,
fine motor testing
• Finger pletysmography (sensitive, not all mild
cases detected, replicability ok)
• Lab: La, CRP, PVK, tromb, CDT, GT, TSH,
kryoglobulins, RF, nucleus-ab, B-gluc, Pt-GlucR1, S-B12-vit, fE-folaat
Diagnosis II
• ENMG, possible carpal tunnel syndrome and
excludes other PNS disease
• Vibration and cold/hot perception threshold
• Neurologist: PNP exclusion
• Fysiatrist: exclusion of TOS or over
extremity/cervical disease
• Angiography not rutinely used
VWF ”clinical problems"
• No white finger findings, only sensory findings
• White finger findings, but also
– generalized polyneuropathy
– cervical radiculopathy
– blood vessel changes mimicing vasculitis
– Primary Raynaud´s disease in the history or
symptoms/findings suggesting it (prevalence 5-6%
in males)
• Occupational rehabilitation is often difficult
(progressed HAVS or wide accompanied
musculoskeletal symptoms)
Whole body vibration
• May increase the rsik of low back pain, disc
protrusion and joint arthritis
• May increase the risk of spontaneous
abortions and premature births
• Difficult to diagnose at indivudual level
• Directive 2002/44/EC
– 8 hour limit 1,15 m/s2
– 8 hour action limit 0,5 m/s2
Treatment and prevention
• Calcium antagonists may help
• Carpal tunnel operation may help, but may also worsen
symptoms
• Stop smoking, reduce risk factors of polyneuropathy
• Stop or decrease exposure to minimum
– technical improvements of tools
– minimum exposure time
– gloves etc.
• Increase temperature
• Periodic health examinations
Literature
• Hannu Vironkannas: ”Peripheral vascular and
nerve disorders in workers exposed to hand-arm
vibration with special reference to snowmobile
drivers”, 1992. (Thesis)
• Pelmear PL, Leong D. Review of occupational
standards and guidelines for hand-arm
(segmental) vibration syndrome (HAVS).
Applied Occupational and Environmental
Hygiene. Vol 15(3):291-302, 2000.